Forget about checking for nukes by monitoring radiation fluxes in the atmosphere, and be careful of relying on satellite photography. The next wave of research for detecting nuclear weapons is going to study changes in the ground, develop tricked-out sensors and look at how networks of nuclear proliferators move around the world.

That's the focus of new research soon to be sponsored by the Defense Threat Reduction Agency, which runs the Pentagon's efforts at locating and controlling material used for the world's deadliest weapons. Beginning later this year, the agency is going to spend between $400,000 and $6 million apiece on research into how to find nuclear weapons through practically every method except old-school atmospheric radiation.

According to an announcement released by the Pentagon agency on Tuesday, the parameters of the research are broad. Work into new technologies that can detect the presence of a nuclear device should focus on "distributed and disposable sensors, re-purposing of existing sensors, combinations of sensors to produce new signature modalities, on-board sensor processing, and reductions to bandwidth and power requirements." The agency wants to develop unconventional "non-radiation indicators of nuclear WMD-related behaviors and activities," like mapping the commercial patterns of "networks" that illicitly traffic in nuclear materials. It's OK to study the impact of a nuclear device on the atmosphere, just as long as researchers focus on modalities like "electrostatic, thermodynamic, mass, acoustic, chemical, or gravitational."

The turn away from atmospheric radiation detection underscores a shift in how nukes get developed. North Korea exploded all three of its nuclear tests underground, limiting the atmospheric fallout and making the world reliant on seismography for learning about the tests and extrapolating data about the weapons' destructive yield. Iran's nuclear program reportedly involves a warren of underground tunnels.

And the alternative nuclear-detection techniques have application beyond the inspection of rogue nuclear programs. The Defense Threat Reduction Agency came into existence two decades ago in order to verify that the former Soviet Union's nuclear weapons and precursor material was locked down. These days, it monitors Russian compliance with nuclear-reduction treaties like 2010's New START, but that monitoring typically depends on negotiated Russian access to nuclear sites. The research here might have some utility for a standoff detection of nuclear weapons, although the announcement hardly specifies that as a goal.

Few of these techniques are actually novel. The Defense Department dabbled, for instance, in modeling and detecting the gravitational signatures of nuclear bombs for decades. And studying the patterns of nuclear proliferators – like Pakistan's old A.Q. Khan network – relies on classic sleuthing techniques, like studying shipping manifests and patterns of commercial activity. But the new research, if it yields anything, shows the Pentagon looking beyond the familiar methods of radiation detection and satellite photography – as those methods are more to tell you about the past as they are about where the next developing nuclear threat takes place.